Mineral dyeing



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'55 may be Patented 9, 1928.

UNITED STATES PATENT OFFICE.

O]? IONTOLAIB, NEW JERSEY, ASSIGNOR TO VIVATEX PBQGESSES,

me, or 1.0m, nnw JERSEY, A .conromrron or nnw JERSEY.

.umnnazr. Drums.

Ho Drawing.

In so-called iron dyeing? of textile materials (including in the latter term not only fabrics of all kinds but also fibres, yarns, threads, etc. to roduce the well known khaki and ong (ong shades,v the practice heretofore has been to impregnate the material with a ferrous compound and at a later stage subject the material toan oxidizing agent for the purpose of converting the ferrous compound into the ferric state. This step, known as aging, is of the highest importance inprior methods,

since the fastness of the color depends 'upon the extent of the oxidation of the ferrous compound, but to carry the oxidation to completion by the method indicated is exceedingly diflicult if not impossible, and in any case it is slow and ineflicient. Efforts have also been made to dye with a ferric compound. So far as I am aware the at tempts have not been successful since the only ferric,- compounds sufliciently soluble to form a dye bath of adequate concentration are nitrate, chloride and sulfate or their derivations, which are prone to dissociate upon drying, thereby setting free the acid radical with the result that the textile material is damaged or tendered. The organic ferric salts which produce but, little,

and in some cases no, tenderingeifect, namely the acetate, tartrate, etc., are of such slight solubility that they have not heretoforebeen usable for the production of pronounced or deep shades of color. Ferrlc formate is v soluble in cold water but hydrolyzes in warm or hot water. v

I have accordingly been ledto devise my present invention, which has for its chief object to provide a dyeing process by which 40 non-tendering ferric salts, mostly organic in nature, can be effectively employed for producing dark as well as light shades of color. To this and other ends the invention comprises the novel features hereinafter de}. scribed. I q

The invention is based uponthe observation that the' solubility of organic salts of' iron and other metals, as for example .ferric acetate, tartrate, and oxalate, (and in the '50 case of ferric formate its solubility in warm water without hydrolyzing) can. be mate frially increased by formic or equivalent a cid, as acetic,-tartaric (racemic and other; denvae tives), and succimc. The solubilizmg acid added to the dye bath before or Application filed December 23, 1926. Serial No. 156,766.

after the ferric salt, but in either case the latter can be dissolved in amount sufiicient to produce verydeep fast shades without damage ontende'ring of'the cellulose materlal. From one to five per cent of formic acid, calculated on the total weight of the bath, is in general suflicient to give a degree of solubility ade uate for the production of shades of a dept or strength scarcely obtaln'able'by the use of ferrous salts. Alkali. salts such as sodium formate, ammonium formate, etc., exert a less degree of solvent stimulation. The solution of difficulty soluble basic salts of aluminum, copper, thorium, zirconium, etc., as for instance their basic acetates, is also stimulated inv the same manner, and in the case of the aluminum,thorium and zirconium salts named such stimulation is necessary since theyare all insoluble in water, or nearly so. I

In carrying out my invention in the pre ferred way the ferric salt may be dissolved directly in a solution of formic acid or other stimulant, but it is more practical, especially where the salt to be used for the dyeing is ferric acetate. to prepare the dye liquor from a'cheap and abundant ferrous salt, such as copperas or ferrous sulfate. The latter is oxidized in its solution by an oxidizing agent such as sodium or potassium chlorate, sodium or potassium di-chromate, nitric acid, sodiumor potassium permanganate, etc. The alkali metal chlorates are marked-' 1y eflicient for the purposebut do not appear to be reatly superior to the di-chromates, the on y apparent disadvantage of the latter being that they introduce chrome salts into the solution when such salts may not be desirable, The-amount of oxidizing agent requireddepends of course-upon the amount of ferrous salt to be oxidized.

When theferrous sulfate in solution has been oxidized to the ferric state, preferably As stated above, one to five per cent of formic acid is ordinarily suflicient. After this addition the sulfurlc acid, free or com-' bine is removed from the liquor by means of a soluble salt (say acetate, formate, succinate or. tartrate), of barium, calcium, lead,

. preferably on drums.

or other element, capable of reacting with the sulfuric acid or sulfate present in the liquor to form an insoluble sulfate. Barium salts are preferred because of the insolu bility of barium sulfate, and the most 0on venient salt for the purpose is barium acetate, but other acetates are sufficientl effective for practical purposes. Using arium acetate, for example, the resulting reaction produces ferric acetate and barium sulfate. The latter is readily separated from the liquor by filtration.

As stated, the presence of the formic acid or other suitable substance, preferably an organic acid, enables the liquor to retain -the acetate or other ferric salt in solution, so that the free and combined sulfuric acid can be removed as described, without the ferric salts being carried down with the insoluble barium sulfate or other sulfate, as would happen if a solvent stimulant were not added prior to the sulfate precipitation. It is, however, feasible to effect the recipi tation of sulfates first, and then reissolve the precipitated ferric salts with the .aid of the solubilizing agent, but the course first described is more advantageous.

.After the insoluble sulfates are removed, as by filtration. or otherwise, the .ferric dye bath can be used in the customary way, the textile material being passed through the bath and then squeezed to eliminate the excess liquor, the impregnated material usually absorbing about seventy percent of its own weight. The squeezed material is then dried,

Festooning is possible, though not as economical as the other method of drying.

\ The impre nated and dried material is now passed t rough a hot alkali solution,

. say caustic soda or soda ash (sodium car-.

'to be bonate) or both, or soda ash and soap, .preferably at about to 100'C., or cold ammonia solution, of suflicient concentration, readily determinable, to decompose without waste ferric' salts and accompanying compounds (for example chromium salts) and form an insoluble iron compound or compounds, as hydroxide, carbonate and oleate, in and upon the fibres of the material. The latter is then washed thoroughly and dried.

' It will be noted that the slow and inefficient aging process, or oxidation after impregnation, is unnecessary in the above method. Theability to secure a completely oxidized deposit on the cloth or other material makes possible a degree of uniformity of shade that is difiicultly if at all obtainable by the prior methods. At the same time the, greater degree ofoxidation, substantially complete if desired, renders the shade correspondingly faster, especially to rain and atmospheric agencies in general, and to laundering,and also enables a given shade produced with less expenditure of,

metallic salts, thereby giving marked economy of operation.

It is to be understood that the invention is not limited to the procedure and details herein specifically described but can be carried out in other ways without departure from its spirit.

I claima 1. In mineral dyeing of textile material, the steps comprising forming with the aid of a solvent stimulant a solution of a ditficultly soluble metallic salt, and impregnating the textile material with the solution.

2. In mineral dyeing of textile material, the steps comprising forming with the aid of a solvent stimulant a solution of a difficultly soluble iron salt, impregnating the textile material therewith, and treating the material to remove from the absorbed iron salt the-acid radical thereof and convert tlle salt into-another insoluble compound.

3. In mineral dyeing of textile material, the steps comprising forming a solution of a metallic sulfate; removing sulfuric acid from the solution by forming therewith an insoluble sulfate and simultaneously forming with the metal of the first mentioned salt another and diflicultly soluble salt of the same, in the presence of a solvent stimulant whereby the difiiculty'. soluble salt is dissolved to form a dye liquor; impregnat ing the textile material with the dye liquor; and treating the textile material to remove the acid radical from the salt absorbed there by and form another insoluble compound.

4. In mineral dyeing of textile material,

the steps comprising forming with the aid of a solvent stimulant a solution of ferric acetate, and impregnating the textile material therewith. Y

5. In mineral dyeing of textile material, the steps comprising treating ferric sulfate, in solution and in the presence of a solvent stimulant, with an acetate capable of reacting with the ferric sulfate ,to form ferric ace- .110 tate insolution and an insoluble sulfate; and treating the textile material with the ferric acetate solution.- 6. In mineral dyeing'of textile material, the steps comprising treating ferric sulfate, 115 in solution and in the presence of a solvent stimulant, with an acetate capable of reacting with the ferric sulfate to-form ferric acetate in solution and an insoluble-sulfate; treating the textile 'material with the ferric 1 acetate solution, and converting the absorbed ferric acetate into another insoluble iron compound. l

7.- In mineral dyeing of textile material, the steps comprising'forming with the aid of a solvent stimulant a solution of an otherwise difiicultly soluble metallic salt of an organic acid, and impregnating the textile material with the solution.

8. In mineral dyeing of textile material,

the steps comprising forming with the aid of a solvent stimulant a solution of an otherwise difiicultly soluble organic salt of iron,

and impregnating the textile material with solution with a-suitable acetate in the presthe solution.

9. In mineral dyeing of textile material, the steps comprising forming with the aid of formic acid as a solvent stimulant a solution of ferric acetate, and impregnating the textile material with the solution.

10. In mineral dyeing of textile material, the steps comprising oxidizing ferrous sulfate in solution to the ferric state, mixing therewith a solvent stimulant and a solution of a suitable acetate to form ferric acetate" the steps comprising'forming a ferrous sulfate solution, treating the same with alkali metal chlorate-to oxidize the ferrous salt to the ferric state, treating the ferric sulfate ence of formic acid to form ferric acetate in solution and an insolublesulfate, tre'ating the textile material with the ferric acetate solution, and thereafter treatingthe textile material with an alkali solution.

- 1.2. In mineral dyeing of textile material, the steps comprising oxidizing ferrous sulfate in solution to the .ferric state, mixing therewith formic acid and a barium acetate solution to form ferric acetate in solution and barium sulfate, treating the textile with the ferric acetate solution, and thereafter converting the absorbed ferric acetate into another iron compound. I

In testimony whereof I hereto affix my signature.

I CLARENCE B. WHITE. 

